In a directed acyclic graph (DAG), a variable that is a common effect of both the exposure and the outcome is called a:
- A Confounder
- B Collider ✓
- C Mediator
- D Effect modifier
Correct answer: B. Collider
Explanation
A collider is a variable that is a common effect of both the exposure and the outcome (or their causes) on a causal pathway. Conditioning on a collider opens a non-causal path and can introduce selection bias or collider bias. A confounder is a common cause of both exposure and outcome; a mediator lies on the causal pathway from exposure to outcome.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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